Chorioretinal vascular abnormalities associated with angioid streaks and pseudoxanthoma elasticum.

OBJECTIVE: To analyze the retinal and choroidal vascular abnormalities in eyes with angioid streaks (AS) associated with pseudoxanthoma elasticum (PXE). METHODS: Color photographs and fluorescein angiograms of 54 eyes of 27 consecutive patients with AS and PXE were examined retrospectively. RESULTS: Four (7%) of the 54 eyes had a major vascular abnormality at the level of the disc; this took the form of a large vascular loop corresponding to an arteriovenous communication between retina and choroid in 3 eyes (6%) and an anastomosis between 2 retinal arteries in 1 eye (2%). CONCLUSION: Analysis of the vascular network in these eyes showed several vascular abnormalities, among which chorioretinal arteriovenous communications appear to be the most dramatic

MONITOR Ionospheric Network: two case studies on scintillation and electron content variability

The ESA MONITOR network is composed of high-frequency-sampling global navigation satellite systems (GNSS) receivers deployed mainly at low and high latitudes to study ionosphere variability and jointly with global GNSS data and ionospheric processing software in support of the GNSS and its satellite-based augmentation systems (SBAS) like the European EGNOS. In a recent phase of the project, the network was merged with the CNES/ASECNA network and new receivers were added to complement the latter in the western African sector. This paper summarizes MONITOR, presenting two case studies on scintillations (using almost 2 years of data measurements). The first case occurred during the major St. Patrick's Day geomagnetic storm in 2015. The second case study was performed in the last phase of the project, which was supported by ESA EGNOS Project Office, when we paid special attention to extreme events that might degrade the system performance of the European EGNOS